262,211 research outputs found
Geochemistry of lead at the old mine area of Baccu Locci (South-East Sardinia, Italy)
No full textAbout a century of exploitation of the galena-arsenopyrite deposit of Baccu Locci in Sardinia (Italy) has caused a
severe, persistent arsenic contamination that extends downstream of the mine for several kilometres. Differently
from As, the aqueous contamination of lead is only localised in the upper part of the mine despite very high Pb
concentrations in geologic materials (waste rocks, tailings, stream sediments, soils) over the whole Baccu Locci
stream catchment. The determination of aqueous and solid Pb speciation in various environmental media of the
Baccu Locci system has pointed out that the peculiar geochemical behaviour of Pb is mainly due to (i) the short
residence time of dissolved Pb in surface and ground water under near-neutral pH conditions and (ii) the low
solubility of plumbojarosite that represents the main secondary Pb-bearing mineral in the Baccu Locci
environment
Isolation of NF-E2-related factor 2 (Nrf2), a NF-E2-like basic leucine zipper transcriptional activator that binds to the tandem NF-E2/AP1 repeat of the beta-globin locus control region
No full textHypersensitive site 2 located in the beta-globin locus control region confers high levels of expression to the genes of the beta-globin cluster. A tandem repeat of the consensus sequence for the transcription factors AP1 and NF-E2 (activating protein 1 and nuclear factor erythroid 2, respectively) is present within hypersensitive site 2 and is absolutely required for strong enhancer activity. This sequence binds, in vitro and in vivo, to ubiquitous proteins of the AP1 family and to the recently cloned erythroid-specific transcription factor NF-E2. Using the tandem repeat as a recognition site probe to screen a lambda gt11 cDNA expression library from K562 cells, we isolated several DNA binding proteins. Here, we report the characterization of one of the clones isolated. The gene, which we named Nrf2 (NF-E2-related factor 2), is encoded within a 2.2-kb transcript and predicts a 66-kDa protein with a basic leucine zipper DNA binding domain highly homologous to that of NF-E2. Although Nrf2 is expressed ubiquitously, a role of this protein in mediating enhancer activity of hypersensitive site 2 in erythroid cells cannot be excluded. In this respect, Nrf2 contains a powerful acidic activation domain that may participate in the transcriptional stimulation of beta-globin genes
Ricostruzione dei flussi di CO2di un ecosistema a macchia mediterranea mediante reti neurali
No full textNell’ultimo decennio sono state realizzate numerose reti di monitoraggio dei flussi di massa ed energia
a scala regionale, che utilizzano come standard di misura la tecnica dell’Eddy Covariance. La continuità del
monitoraggio dei flussi è una condizione difficilmente realizzabile a causa sia della complessità degli apparati di misura
sia di alcune limitazioni di carattere modellistico: in generale dopo i controlli di congruità fisica e biologica, non più del
65% dei dati risulta utilizzabile per la costruzione dei bilanci annuali. Negli ultimi anni sono state sviluppate
metodologie per la ricostruzione dei dati mancanti dei flussi di energia e materia negli ecosistemi terrestri; tuttavia,
attualmente non esiste una metodologia di ricostruzione standardizzata. In questo lavoro vengono realizzati modelli
basati sulle reti neurali per la ricostruzione dei flussi di CO2in un ecosistema a macchia mediterranea; le prestazioni
fornite da tali modelli vengono confrontate con quelle di altre tecniche recentemente proposte dalla comunità
internazionale. I dati sono stati raccolti nel corso del biennio 1998-99 in un sito sperimentale del progetto europeo
MEDEFLU situato nella Sardegna nord-occidentale. I modelli basati sulle reti neurali hanno fornito in genere
prestazioni superiori rispetto agli altri metodi, con valori dell’errore quadratico medio compresi tra 0.9 e 2.9 μmol m-2 s-
1 di CO2. Questi risultati confermano le possibilità applicative delle reti neurali nella ricostruzione dei flussi provenienti
da reti di monitoraggio
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mutations in the Zn finger of EKLF that retain binding to the DNA reduce its ability to transactivate the γ-globin gene
No full textA novel splicing defect (IVS6+1G > T) in a patient with pseudovitamin D deficiency rickets
No full textA 15-month-old boy with severe rickets, that by clinical analysis was diagnosed as affected by hereditary pseudovitamin D deficiency rickets (PDDR), was evaluated for mutations in the 25OHD(3) 1alpha-hydroxylase gene. Molecular analysis showed a double heterozygous state for a novel splicing mutation in the invariant dinucleotide of the donor site of IVS6 and a 7 nucleotide insertion in the exon 8, which is common in different ethnical backgrounds. (C) 2002, Editrice Kurtis
A novel silent beta-thalassemia mutation in the distal CACCC box affects the binding and responsiveness to EKLF
No full textThe silent beta-thalassemia mutation, beta(+)-101C --> T, is the only mutation currently described in the distal beta-globin CACCC box. We present a novel mutation, a C --> G transversion, in the same position. Expression analysis in heterozygous subjects demonstrated that the mutation determines a 20% reduction in the output of the P-globin gene. DNA-protein interaction and transactivation analysis correlated the decrease in the beta-globin synthesis with the reduced binding and transactivation of EKLF to the mutant promoter. These data predict that the beta-101C --> G mutation will display a silent thalassemia phenotype similar to that of the beta-101 C --> T mutation
A novel missense mutation (C84R) in a patient with type II vitamin D-dependent rickets
No full textA 7-year-old boy with severe rickets that by clinical analysis was diagnosed as affected by type II vitamin D-dependent rickets, was evaluated for mutations in the vitamin D receptor gene (VDR). The molecular analysis showed a homozygous state for a novel missense mutation (C84R) in a highly conserved nucleotide in the second Zn finger of the DNA binding domain
Deficiency in interferon type 1 receptor improves definitive erythropoiesis in Klf1 null mice
No full textA key regulatory gene in definitive erythropoiesis is the transcription factor Krüppel-like factor 1 (Klf1). Klf1 null mice die in utero by day 15.5 (E15.5) due to impaired definitive erythropoiesis and severe anemia. Definitive erythropoiesis takes place in erythroblastic islands in mammals. Erythroblastic islands are formed by a central macrophage (Central Macrophage of Erythroblastic Island, CMEI) surrounded by maturating erythroblasts. Interferon-β (IFN-β) is activated in the fetal liver’s CMEI of Klf1 null mice. The inhibitory effect of IFN-β on erythropoiesis is known and, therefore, we speculated that IFN-β could have contributed to the impairment of definitive erythropoiesis in Klf1 knockout (KO) mice fetal liver. To validate this hypothesis, in this work we determined whether the inactivation of type I interferon receptor (Ifnar1) would ameliorate the phenotype of Klf1 KO mice by improving the lethal anemia. Our results show a prolonged survival of Klf1/Ifnar1 double KO embryos, with an improvement of the definitive erythropoiesis and erythroblast enucleation, together with a longer lifespan of CMEI in the fetal liver and also a restoration of the apoptotic program. Our data indicate that the cytotoxic effect of IFN-β activation in CMEI contribute to the impairment of definitive erythropoiesis associated with Klf1 deprivation
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